1. Field of the Invention
The present invention relates to a liquid jet head for ejecting liquid from a nozzle to record characters or graphics on a recording medium, or to form a functional thin film thereon, and a liquid jet apparatus using the liquid jet head.
2. Description of the Related Art
In recent years, there has been used an ink-jet type liquid jet head for ejecting ink droplets on recording paper or the like to record characters or graphics thereon, or for ejecting a liquid material on a surface of an element substrate to form a functional thin film thereon. In such a liquid jet head, ink or a liquid material is supplied from a liquid tank via a supply tube to the liquid jet head, and ink or a liquid material filled into a channel is ejected from a nozzle which communicates to the channel. When liquid is ejected, the liquid jet head or a recording medium is moved to record characters or graphics, or to form a functional thin film in a predetermined shape.
Conventionally, for the purpose of miniaturizing a liquid jet head and of achieving higher density recording, an ink jet head 100 has been proposed in which actuator units are multilayered and integrally formed. FIG. 12 is a schematic view of an ink jet head described in Japanese Patent Application Laid-open No. Hei 10-146974 (FIG. 1 of Japanese Patent Application Laid-open No. Hei 10-146974). In the ink jet head 100, eight actuator units 120 to 190 each including a cover plate 121 and a base plate 122 are laminated, and one nozzle plate 111 is bonded to end faces thereof. The units have basically the same structure. Specifically, a plurality of ink chambers 124 in parallel with one another are formed in a surface of each base plate 122. Each ink chamber 124 is sandwiched between two piezoelectric elements, and openings in an upper surface of the ink chambers 124 are covered by the cover plate 121.
A cover plate 131 at a laminated portion includes a projecting portion 131a on a side opposite to the nozzle plate 111. An output side electrode 128 and an input side electrode 126 are formed and a driver IC chip 125 is provided on the projecting portion 131a. A flexible substrate (hereinafter referred to as FPC) 127 is connected to the projecting portion 131a to be electrically conductive to the input side electrode 126. A plurality of nozzles 112 communicating to the ink chambers 124, respectively, in the base plates 122 are formed in the nozzle plate 111. A control signal is input to the driver IC chip 125 in each actuator unit through the FPC 127 and the input side electrode 126, and a drive signal is supplied by the driver IC chip 125 to the piezoelectric element via the output side electrode 128 and a drive electrode 123 formed on the end face of the base plate 122 on the nozzle plate 111 side to drive the ink chamber 124. Pressure is applied to ink filled into the ink chamber 124 in accordance with a drive signal to eject an ink droplet from the nozzle 112.
FIG. 13 is a schematic sectional view of a liquid jet head 220 described in Japanese Patent Application Laid-open No. 2008-207350. In the liquid jet head 220, head chip bodies 227 each of which is formed by laminating an actuator substrate 225 and a cover plate substrate 226 are laminated in four layers, and one nozzle plate 223 is bonded to the other edge sides 221b thereof. One edge side 221 A of the actuator substrate 225 in one layer in the head chip bodies 227 laminated in four layers protrudes from the one edge side 221 A of the actuator substrate 225 in the layer immediately thereon. An FPC 213 is connected to a substrate connection surface 228 which is an upper surface of a protruding portion of each actuator substrate 225.
A plurality of channels 229 are formed in parallel with one another at substantially the same place in a P direction in each actuator substrate 225. Each channel 229 is sandwiched between side walls 229b, and an electrode 231 is formed on each side wall 229b. The electrode 231 is provided so as to extend to the substrate connection surface 228, and is electrically conductive to wiring (not shown) formed on the FPC 213 bonded to the substrate connection surface 228. A plurality of nozzles 223a are formed in the nozzle plate 223, and the plurality of nozzles 223a communicate to the plurality of channels 229, respectively, in each actuator substrate 225. In the cover plate substrate 226, there are formed an ink chamber 232 communicating to the respective channels 229 and ink supply holes 234 having one ends open to the ink chamber 232 and the other ends communicating with the ink chamber 232 in the head chip body 227 in the layer immediately thereunder. Therefore, ink supplied to the ink chamber 232 in the head chip body 227 in the uppermost layer is supplied to the respective channels 229 in the head chip body 227 in the uppermost layer and to the ink chambers 232 in the head chip bodies 227 in lower layers, and thus, is supplied to the channels 229 in all the head chip bodies 227.
In the ink jet head 100 disclosed in Japanese Patent Application Laid-open No. Hei 10-146974, a drive signal supplied to an ink chamber 124 in the actuator unit 120 in an upper layer is supplied from the driver IC chip 125 provided in the actuator unit 130 in the layer immediately thereunder. Further, one nozzle plate 111 is used. Therefore, the quality of the ink jet head 100 can be determined by a trial run only after the actuator units 120 to 190 in all the layers are laminated and the assembly is completed.
Further, in the ink jet head 100 disclosed in Japanese Patent Application Laid-open No. Hei 10-146974, when a conventionally used step of press-bonding the FPC 127 from the top side of FIG. 12 to the cover plate 131 for connection is reviewed, it is difficult to connect the FPCs 127 to the respective layers after the actuator units 120 to 190 in the respective layers are laminated. Therefore, the actuator units 120 to 190 to each of which the FPC 127 is connected in advance need to be prepared, and the actuator units 120 to 190 to each of which the FPC 127 is bonded need to be laminated in sequence. In that case, it is difficult to bond the actuator units 120 to 190 so that the end faces thereof on the nozzle plate 111 side are aligned to be flush with one another. The drive electrodes 123 are provided on the end faces of the actuator units 120 to 190 on the nozzle plate 111 side, and thus, after the actuator units 120 to 190 are bonded together, it is impossible to grind the end faces thereof on the nozzle plate 111 side to shape the end faces to be flush with one another. Further, it is necessary to form a large number of nozzles 112 in the one nozzle plate 111 and to accurately align the nozzles 112 with the ink chambers 124 in the multilayered actuator units 120 to 190 formed by lamination, which requires highly developed assembly operation.
In the liquid jet head 220 disclosed in Japanese Patent Application Laid-open No. 2008-207350, after the liquid jet heads 220 are laminated, it is possible to connect the FPC 213 to the one edge side 221 A of each head chip body 227. However, after the head chip bodies 227 are laminated and bonded together, the one nozzle plate 223 is bonded to the laminate, and thus, similarly to the case of the above-mentioned ink jet head 100 disclosed in Japanese Patent Application Laid-open No. Hei 10-146974, it is necessary to accurately align a large number of nozzles 223a with a large number of channels 229, which requires highly developed assembly operation. Further, similarly to the case of Japanese Patent Application Laid-open No. Hei 10-146974, the quality can be determined by a trial run only after the assembly is completed.